To suppress deterioration in quality and yield in semiconductor device manufacturing processes, it is important to quantitatively understand the cleanliness levels of various manufacturing apparatuses and process sites, and to appropriately control the manufacturing processes. To this end, there is a need to detect a foreign substance, flaw, defect, dirt, etc. (hereinafter collectively referred to as a foreign object) present on the surfaces of the semiconductor wafers (hereinafter, referred to simply as wafers) and statistically control the kind, size, quantity, etc. of a foreign object detected. Accordingly, wafer surface inspection with surface inspecting apparatuses has traditionally taken place in the semiconductor device manufacturing processes.
A known type of surface inspecting apparatus for detecting a foreign object on the surface of a wafer achieves the detection by irradiating the wafer surface with such inspection light as laser light, and detecting the light reflected or scattered from the wafer surface (See Patent Document 1, for example).